Fluid translating device



Aug. 11, 1970 I DADIAN ET AL 3,523,746

FLUID TRANSLATING DEVICE Filed Oct. 51, 1968 5 Sheets-Sheet 1 a j 112 3 11,6 1% g f ye d% Aug. 11, 1970 DADlAN ET AL 3,523,746

FLUID TRANSLATING DEVICE Filed 001;. 31, 1968 5 Sheets-Sheet 2 Aug. 11, 1979 DADIAN ET AL 3,523,746

FLUID TRANSLATING DEVICE 5 SheetsSheet 5 Filed Oct. 31, 1968 Aug. 11, 1970 L H. DADlAN ET AL 3,523,746

FLUID TRANSLATING DEVICE Filed Oct. 31, 1968 5 Sheets-Sheet 4.

Aug. 11, 1979 H, DAEHAN ET AL 3,523,746

FLUID TRANSLATING DEVICE Filed Oct. 51, 1968 5 Sheets-Sheet 5 United States Patent US. Cl. 41826 19 Claims ABSTRACT OF THE DISCLOSURE A fluid translating device, such as a pump, having a pumping chamber with pumping elements including a slotted rotor with movable vanes, a movable ring surrounding the rotor for controlling the movement of the vanes outwardly of the rotor, and pressure plates on opposite sides of the rotor and ring having ports therein for conducting fluid to and from the vanes. A peripherallysealed pressure area surrounds the pressure ports to urge the pressure plates toward the rotor and movable ring to oppose the pressure generated by the pump and maintain an effective seal to reduce pump leakage. A spacer member is positioned between the pressure plates against which the pressure plates abut to limit inward movement of the pressure plates to avoid binding the movable ring. Pressure compensation control of the movable ring is provided by opposed fluid pistons. Provision is made for in termittent lubrication of the bearings mounting the rotor shaft during operation of the pump by passages placed in communication during revolution of the pump rotor. Hertz stress on the movable ring of the pump is reduced by curved ends on the movable vanes.

BACKGROUND OF THE INVENTION This invention relates to a fluid translating device and, more particularly, a variable volume vane type pump having new and improved structure for control of the movable ring of the pump, for reducing leakage in the pump and for providing overall improved operation in a pump handling relatively high pressures.

It has been generally known in variable volume vane type pumps to urge pressure, or port, plates laterally against the pumping elements to reduce leakage in operation of the pump. However, such systems have not maximized the reductions of leakage while still controlling the amount of forces acting to urge the pressure plates toward opposite sides of the rotor with provision for maintaining minimum spacing of the pressure plates to reduce restraint on the movable ring and wear on the relatively movable parts.

Additional problems involved in the prior art have to do with shaft lubrication, stresses in the movable ring, and pump casing size required by the size of the movable ring, all of which have been solved by features of the invention described hereinafter.

SUMMARY An object of this invention is to provide a new and improved fluid translating device and, more particularly, a variable volume vane type pump having one or more of the features of: improved mounting and control of the movable ring of the pump; reductions in pump leakage by controlled forces urging the pressure plates against the rotor and movable ring of the pump; controlled positive lubrication of the rotor shaft bearings; effective sealing of the ports in the pressure plates; and improved coaction between the movable vanes and movable ring of the pump.

Further objects and advantages will become apparent from the following detailed description taken in connection with the accompanying drawings.

3,523,746 Patented Aug. 11, 1970 "ice BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a central plan section of the fluid translating device;

FIG. 2 is a vertical section taken generally along the line 22 in FIG. 1;

FIG. 3 is a vertical section taken generally along the line 33 in FIG. 1;

FIG. 4 is an elevational view of one side of a pressure plate and taken generally along the line 44 in FIG. 1;

FIG. 5 is a view of the opposite side of the pressure plate taken generally along the line 5-5 in FIG. 1;

FIG. 6 is a fragmentary view of the rotor and shaft and associated structure showing the parts rotatably positioned to provide for lubrication of a bearing positioned to the left of the structure shown in FIG. 6;

FIG. 7 is an enlarged view of the seal structure for the pressure plate;

FIG. 8 is a fragmentary elevational view of a pumping vane;

FIG. 9 is a view similar to FIG. 3 of a second embodiment of the fluid translating device; and

FIG. 10 is a vertical section, taken generally along the line 10-10 in FIG. 9.

DESCRIPTION OF THE EMBODIMENTS While this invention is susceptible of embodiment in many different forms, there is shown in the drawing and will herein be described in detail an embodiment of the invention together with a modification thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. The scope of the invention will be pointed out in the appended claims.

One embodiment of the fluid translating device is disclosed in FIGS. 1-8 and shown generally in FIGS. 1, 2 and 3 and comprises a vane-type unit and, in the description, is specifically described as a variable volume vane type pump.

The pump has a two-part casing including a first part 10 having a mounting base 11 and a cylindrical chamber 12 for receiving the pumping elements to be described. A second casing part 15 has a cylindrical section 16 which fits into the cylindrical chamber 12 to close off the chamber. The casing parts are sealed together by a seal 17 positioned therebetween and are held together by threaded attaching members 18.

The pumping elements include a rotor 20 having a series of outwardly-extending slots 21, each of which receives an outwardly movable vane 22, shown particularly in FIG. 8, with the outward extent of the vane movement being controlled by a variably positionable ring 23 in the form of an annular member surrounding the rotor 20.

The rotor 20 is rotatably mounted by an integral shaft having sections 25 and 26 extending outwardly from opposite sides of the rotor to rotatably fit in bearings 27 and 28, respectively, received in concentric openings 29 and 30 in the casing parts 15 and 10. The opening 29 in casing part 15 does not extend to the outer face of the casing part; however, the section 26 of the rotor shaft extends outwardly of the pump casing for a drive connection. A seal 31 is fitted in a recess 32 in the casing part 10 to surround and seal the rotor shaft section 26.

In order to form closed pumping spaces between adjacent vanes 22 and the movable ring 23, the sides of said spaces are closed off by a pair of pressure plates 40 and 41 positioned in the chamber 12 and at opposite sides of the rotor 20. The pressure plate 40 is shown particularly in FIGS. 4 and 5. Each of the pressure plates is of generally the same construction and reference will be made particularly to pressure plate 40 in describing the construction thereof. The pressure plate is generally discshape and of composite construction, with the major section 42 thereof being formed of conventional material. The major section has a face section 43 bonded thereto with a surface layer of bearing-type material, such as bronze, to have facial engagement with the sides of the rotor 20, the vanes 22, and the movable ring 23. A pair of pressure ports 45 and 46 extend through the pressure plate 40 and communicate with an arcuate pressure channel 47 in the plate section 43, which is of an arcuate extent to communicate with the spaces between a plurality of the vanes 22. The section 43 also has a vane balancing groove 48 which communicates with the inner end of the rotor slots 21 to urge the vanes outwardly and provide partial pressure balancing for the vanes 22 during crossover. Pressure fluid is supplied to the balancing groove 48 through a pair of passages 49 and 50 which extend between the ports 45 and 46 and the balancing groove 48. With the foregoing structure as the fluid is delivered by the pump, it discharges from the spaces between vanes 22 through the ports 45 and 46 for discharge from the pump.

The pressure plate 40 has a central opening 51 to receive the rotor shaft section 26 with a loose fit and a series of peripheral notches 52, 53 and 54 which lie outwardly of the movable ring 23 and communicate with case drain for the pump.

The pressure plate 40 has a pair of suction ports 55 and 56 which extend through the pressure plate and communicate with a suction groove 57 in the plate section 43 and which has an arcuate extent suflicient to supply fluid to a plurality of spaces between adjacent vanes 22. An arcuate vane balancing groove 58 is supplied with fluid through a pair of passages 59 and '60 in order to balance the vanes.

In order to have a pump of high efliciency and with reduced leakage, the pressure plate 40 is urged toward the rotor 20 and movable ring 23 by pump pressure. The necessary force is obtained by scaling 011? an area of the outer face of the pressure plate of a size which, when subjected to pump pressure slightly exceeds the forces generated by fluid under pressure between the vanes 22 in the pressure side of the pump. As pump pressure varies, the force will vary in direct proportion thereto. This pressure balancing area is shown particularly in FIG. 4 as a kidney-shaped area 65 which is defined by a correspondingly-shaped continuous groove 66 surrounding the pressure ports 45 and 46 and which receives seal structure which seals against the adjacent face 67 of the first casing part 10. This seal structure is shown particularly in FIG. 7 and comprises a kidney-shaped seal member 68 of material, such as Teflon, which is urged against the casing face 67 by pressure fluid which moves outwardly from the area 65 into the groove 66 and acts against an O-ring 69 which engages against a flexible seal member 70, such as fish paper, whereby the pressure causes deformation of the O-ring 69 to seal against the bottom of the groove 66 and urge the seal member 68 outwardly against the adjacent face of the casing. The seal components are all continuous and generally of the same shape as the groove 66 to a continuous seal around the pressure balancing area.

Further to minimize leakage, a kidney-shaped groove 75 is provided in the section 42 of the pressure plate surrounding the suction ports 55 and 56 and receives a similarly-shaped O-ring 76 to seal against the face 67 of the casing part and preclude leakage of fluid from the area surrounding the suction ports.

The construction and operation of the pressure plate 41 is substantially the same as the pressure plate 40, as is evident in FIGS. 1 and 2 and the same parts have been given the same reference numeral with a prime aflixed thereto. Inasmuch as the balancing ports 48' and 58' communicate with the balancing ports 48 and 58 of pressure plate 40, the pressure plate 41 does not require the passages 49 and 50, 59 and 60 of the pressure plate 40.

The suction ports 55 and 56 of the pressure plate 40 are connected to tank by a passage 80 extending upwardly within the casing part 10 from the bottom thereof and having a laterally-extending upper end communicating with the suction ports. Fluid delivered by the pump discharges from the pressure ports 45 and 46 and flows through a lateral arcuately-shaped passage 81 to a vertical passage 82 in the casing part 10 whereby suitable fluid connections can be made to the pump at the bottom thereof.

With pressure balancing of the pressure plates 40 and 41 caused by the kidney-shaped areas on the outer faces thereof, it is important to limit the pressure of the pressure plates against the rotor and movable ring to minimize wear on the inner faces of the pressure plates resulting from rotation of the rotor and to prevent binding of the movable ring which must move to provide the variable volume control of the pump. This result is accomplished by use of a spacer member positioned between the pressure plates 40 and 41 and, as shown, comprises a spacer ring surrounding the movable ring and in spaced relation thereto. This ring defines a minimum spacing between the pressure plates of a dimension to permit the pressure plates to effectively seal against the rotor 20, vanes 22, and movable ring 23 without undue pressure thereon.

The movable ring 23 is controlled in its positioning relative to the rotor 20 to control the output of the pump by hydraulic means including a pair of opposed hydraulic pistons 91 and 91a engaging the outer surface of the movable ring 23. The porting in the pressure plates 40 and 41 is arranged to have the force vector of the pumping forces act upwardly on the ring 23 in a direction toward a thrust pin 92 threaded in the casing part 10 and having a lower end 93 extending through an opening 94 in the spacer ring 90 to support the movable ring against the pumping forces. This structural relation results in a minimal amount of force derived from the pumping action acting along a line which is coincident with the axes of the pistons 91 and 91a.

The piston 91 is movable in a chamber 95 in the casing part and has an operative end 96 extending through an opening 97 in the spacer ring 90 to engage the outer surface of the movable ring 23. The chamber 95 is closed off by a cover 98 secured to the casing part 10 and with a recess 99 providing a fluid chamber adjacent the end of the piston chamber 95. The piston 91 is always subjected to the pressure existing in the pressure ports 45 and 46 by communicating passages 100, 101 and 102 formed in the second casing part 15 which extend between the kidney-shaped pressure area at the back side of the pressure plate 41 and a passage 103 formed in the casing part 10 which communicates with the fluid chamber 99 at the outer end of the piston chamber 95. As a result, the piston 91 will urge the movable ring 23 away from the eccentric position shown in FIG. 3 relative to the rotor 20 toward a position in which the ring is concentric with the rotor to reduce the volume of the pump output.

The actual position of the movable ring 23 is controlled by the hydraulic piston 91a acting in opposition to the piston 91. The piston 91a is movable in a chamber 105 formed in the casing part 10 and has a reduced end 106 extending through an opening 107 in the spacer ring 90 to engage against the outer surface of the movable ring 23. The cross-sectional area of the piston 91a is approximately twice that of the piston 91.

The piston 91a has an internal recess 110, shown in FIG. 1, opening to the rear end thereof which receives a spring 111 urging the piston 91a toward the ring 23. The end of the piston chamber 105 is closed off by a pressurecompensating servo valve assembly including a body 112 fixed to the casing part 10.

The pressure compensator control valve is disclosed and claimed in a copending application and only general reference is made herein to the valve. This valve has a bore 113 in the body 112 extending longitudinally thereof mounting a valve spool 114 which is urged toward the right as viewed in FIG. 1 by an adjustable control spring 115. The valve bore communicates with three passages, with a first passage 116 receiving fluid from the pressure ports of the pump. A second passage 117 communicates with the end of the piston chamber 105 and a third passage 118 connects to case drain of the pump. A pair of lands 119 and 120 on the valve spool lie to either side of the passage 117 and control the connection of this passage to either the pressure passage 116 or the drain passage 118. Pressure fluid is delivered to the right-hand end of the valve bore 113 to act against the right-hand end of the spool 114 in opposition to spring 115 by an internal passage in the valve spool having an inlet 121 and an outlet 122. The valve bore is closed by a threaded cap 123.

Pressure fluid from the pump is supplied to the passage 116 by a series of passagesformed in the body parts and extending between the kidney-shaped pressure area at the back side of the pressure plate 41 and the passage 116. These passages include connecting passages 130 and 131 and 132 in the body part 15 and a passage 133 in the valve body part 10. The pressure at which the pressure compensator valve will start to obtain compensating action by movement of the ring 23 from the position of FIG. 3 toward a concentric position is set by the adjustable spring 115. Prior to such time, the control spring 115 urges the valve stem 114 to the right to permit fluid communication between the passages 116 and 117, past the land 119 whereby the piston 91 is subjected to outlet fluid pressure to urge the ring toward the right as viewed in FIG. 3. As the pressure increases, this pressure acts against the right-hand end of the valve spool 114, as viewed in FIG. 1, to urge the spool and land 119 to the left against the Spring 115 and reduce the communication between the passages 116 and 117. Upon a suflicient increase in pump pressure, communication is blocked between passages 116 and 117 by land 119 and opened between the control passage 117 and the tank passage 118 past land 120, whereby fluid can flow todrain to reduce the pressure acting on the piston 91a whereby the piston 91 controls to urge the movable ring 23 to a substantially concentric relation with the rotor 20.

A case drain passage 140 is shown in FIGS. 1 and 2 and directly communicates with fluid passing through the rotor shaft bearing 28 and with the outer perimetral space surrounding the pressure plates 40 and 41 through a passage 141 communicating therewith as shown in FIG. 1. This latter space also receives fluid passing through the bearing 27 by means of a passage 142, shown in FIG. 2, and receives fluid from the outlet passage 118 of the pressure compensating valve by way of a passage 143 in casing body part 10 communicating with the passage 118, as shown in FIG. 3. This communication is through an opening 144 in the spacer ring 90.

Provision is made for obtaining controlled lubrication of the rotor shaft sections and 26 and their associated bearings 27 and 28 by intermittent fluid jets from the pump. This controlled lubrication provides for a charge of 2fluid to each bearing once in each revolution of the rotor The structure for accomplishing this is shown particularly in FIGS. 5 and 6 wherein the inner section 43 of the pressure plate has a radial slot 150 opening to the center opening 51 of the pressure plate and terminating short of the pressure balancing groove 48. This slot coacts with a radial notch 151 on the face of the rotor 20 which is a short distance from the inner end of the rotor and which spans the pressure balancing groove 48 and the radial slot 150 of the pressure plate once in each revolution of the rotor to connect the pressure balancing groove 48 with the rotor shaft section whereby a jet of fluid under pressure is injected into the adjacent bearing.

6 The other pressure plate has a similar radial slot which coacts once in each revolution with a similar adjacent radial notch 151a on the rotor side to inject a jet of oil into the other shaft bearing.

An additional feature of the pump construction is in the shaping of the vanes with a radius at the tip thereof to reduce Hertz stress on the movable ring 23. This is shown in FIG. 8 wherein a fragmentary detail of a pump vane is shown. The pump vane 22 has an upper end provided with a pair of upwardly inclined converging surfaces 160 and 161 which are connected by an outer end 162 having a convexly curved surface.

A modified form of the fluid translating device is shown in FIGS. 9 and 10, which is of generally the same construction as the embodiments of FIGS. 1 to 8, except for the construction of the thrust block for the movable ring and the thickness of the latter and parts similar to the embodiment of FIGS. 1 to 8 have been given the same reference numerals with 200 added thereto.

In the embodiment of FIGS. 9 and 10, a thrust block construction is provided to react against the pumping forces and directly against the movable ring 223 and to provide for a reduced thickness of the movable ring 223. This thrust block construction is located in a recess 400 in the pump body part 210 and embodies a cap 401 sealed to the body part by an O-ring 402 and which has an insert 403 against which a hardened steel ball 404 engages. The thrust block has an upper cylindrical end 410 which loosely fits in the recess 400 and an integral lower generally rectangular end 411 with a pair of spaced surfaces 412 and 413 each making line contact with the outer surface of the movable ring 223. The back side of the thrust block has an insert 414 engaging against the ball 404 whereby the thrust block can pivot within the recess 400 on the ball 404 to follow the ring 223 in its movement. The load on the pivot ball is substantially reduced by supplying system pressure to the space between the back of the thrust block and the cap 401 through a passage 420 which communicates with the pressure passage 282. This space is sealed by an outwardly urged seal ring 421 in a groove in the thrust block which seals the perimeter of the thrust block to the wall of the recess 400 but still permits slight rocking movement of the thrust block. The overall area of the back end of the thrust block 410 is dimensioned to have system pressure acting thereon function to reduce by approximately 60%- the loading on the pivot ball 404.

The two point support of the movable ring reduces the maximum loading on any one part of the ring as compared to a single point support in the embodiments of FIGS. 1 to 8 whereby the movable ring 223 can be of a lesser radial thickness for the same pressure rating of the pump. This will be noted by the reduced radial thickness of the ring 223 as compared to the radial thickness of the ring 23 in the embodiment of FIGS. 1 to 8.

The spacer ring 290 is provided with an opening 430 of a size to permit the lower end of the thrust block 411 to extend into engagement with the movable ring 223.

We claim:

1. A variable volume vane type pump comprising a two-part casing with one part of the casing having a cylindrical chamber to receive a plurality of components including a slotted rotor with movable vanes, a movable ring surrounding the rotor, and a pair of pressure plates disposed one at each side of the rotor and ring, means between said casing and the adjacent side of each of said pressure plates defining a peripherally sealed pressure area whereby fluid under pump pressure urges said pressure plates toward the rotor and ring to oppose the pressure generated by the pump, and a spacer rin-g surrounding said movable ring against which said pressure plates abut to limit movement of the pressure plates and permit free unbound movement of the movable ring.

2. A variable volume vane type pump as defined in claim 1 including opposed pistons for controlling the posit-ion of the movable ring and each having an end engaging the ring, and a pair of openings in the spacer rin-g through which said ends extend to engage the movable ring.

3. A variable volume vane type pump as defined in claim 1 including a thrust block for opposing a force vector on the movable ring created by the pumping forces and having a pair of spaced apart faces engaging with line contact the outer perimeter of the movable ring means mounting the thrust block for rocking movement as the movable ring shifts position, and means for applying pump pressure to the back side of the thrust block.

4. A variable volume vane type pump as defined in claim 3 wherein said thrust block is loosely mounted and supported by a ball for the rocking movement.

5. A variable volume vane type pump as defined in claim 4 wherein said thrust block has a surface at the back side of a size subjected to pump pressure to create force suflicient to counteract a major part of the ring load acting on the thrust block, and a peripheral seal member on the thrust block.

'6. A variable volume vane type pump as defined 1n claim 1 wherein said movable vanes have rounded ends engageable with the interior of the movable rmg to reduce Hertz stress on said movable ring.

7. A variable volume vane type pump as defined in claim 1 wherein said slotted rotor has a shaft rotatably supported at either side of the rotor in bearings, and means for injecting fluid under pressure into the bearings at least once in each revolution of the rotor, said fluid internall su lied by the pump. til A variable v dlbme vane type pump as defined in claim 7 wherein said fluid injecting means includes a radial slot positioned between the center of one pressure plate and an adjacent pressure port 1n the pressure plate and a radial notch on a side face of the rotor ad acent the rotor shaft which spans said port and slot once in each revolution of the rotor.

9. A variable volume vane type pump as defined n claim 1 wherein each of said pressure plates has a pair of arcuate radially spaced pressure ports for transmitting fluid under pressure from one side of the pressure plates to the other, said pressure ports being located wlthm said sealed pressure area, and said means defimng said sealed pressure area comprising a continuous groove 11'! the rear plate surrounding said pressure ports and a pressure seal positioned in said groove and urged against the caslng by pressure of fluid in said groove behind the seal.

10. A variable volume vane type pump as defined in claim 9 wherein said pressure plates have suction ports for transmitting inlet fluid from one side of the pressure plate to the other, and a sealed kidney-shaped suction area surrounding said suction ports defined by a continuous groove with an O-ring therein sealing the space between the pressure plates and adjacent walls of the casing.

11. A variable volume vane type fluid translating device comprising a casing having a chamber to receive a plurality of components including a slotted rotor with movable vanes and a movable ring surrounding the rotor, a pressure plate at a side of the rotor and movable ring and having a pressure port, a kidney-shaped sealed pressure area between the adjacent faces of the pressure plate and the casing surrounding said pressure port whereby fluid under pressure urges the pressure plate toward the rotor and ring to oppose the pressure at the opposite side of the pressure plate, and a spacer member against which said pressure plate abuts to permit free movement of the movable ring.

12. A device as defined in claim 11 including opposed pistons for controlling the position of the movable ring and each having an end engaging the ring, and a pair of openings in the spacer ring through which said ends extend to engage the movable ring.

13. A variable volume vane type fluid translating device comprising, a casing having a chamber to receive a plurality of components including a slotted rotor with movable vanes and a movable ring surrounding the rotor, at pressure plate at a side of the rotor and movable ring and having a pressure port, a kidney-shaped sealed pressure area between the adjacent faces of the pressure plate and the casing surrounding said pressure port whereby fluid under pressure urges the pressure plate toward the rotor and ring to oppose the pressure at the opposite side of the pressure plate, and a thrust block for opposing a force vector on the movable ring having a pair of legs with faces engaging the outer perimeter of the movable rmg.

14. A device as defined in claim 13 wherein the thrust block is mounted for rocking movement on a ball supported by the casing, and means for applying pressure to the back side of the thrust block to reduce the loading on the ball.

15. A variable volume vane type fluid translating device comprising, a casing having a chamber to receive a plurality of components including a slotted rotor with movable vanes and a movable ring surrounding the rotor, a pressure plate at a side of the rotor and movable ring and having a pressure port, a kidney-shaped sealed pressure area between the adjacent faces of the pressure plate and the casing surrounding said pressure port whereby fluid under pressure urges the pressure plate toward the rotor and ring to oppose the pressure at the opposite side of the pressure plate, and said movable vanes having rounded ends engageable with the interior of the movable ring to reduce Hertz stress on said movable ring.

16. A variable volume vane type fluid translating device comprising, a casing having a chamber to receive a plurality of components including a slotted rotor with movable vanes and a movable ring surrounding the rotor, a pressure plate at a side of the rotor and movable ring and having a pressure port, a kidney-shaped sealed pressure area between the adjacent faces of the pressure plate and the casing surrounding said pressure port whereby fluid under pressure urges the pressure plate toward the rotor and ring to oppose the pressure at the opposite side of the pressure plate, a shaft carrying said slotted rotor, a bearing supporting said shaft, and means for injecting fluid under pressure into the bearing at least once in each revolution of the rotor including a radial notch on a side face of the rotor and a radial slot in the pressure plate opening to said shaft with said radial notch connecting fluid in the chamber with said slot once in each revolution of the shaft.

17. A variable volume vane type pump comprising, a casing having a chamber to receive a plurality of components including a slotted rotor with movable vanes and a movable ring surrounding the rotor, a pressure plate at a side of the rotor and movable ring and having a pressure port, a kidney-shaped sealed pressure area between the adjacent faces of the pressure plate and the casing surrounding said pressure port whereby fluid under pressure urges the pressure plate toward the rotor and ring to oppose the pressure at the opposite side of the pressure plate, a suction port in said pressure plate, and a sealed kidney-shaped suction area surrounding said suction port defined by a continuous groove with an O-ring therein sealing the space between the pressure plate and adjacent wall of the casing.

.18. A variable volume vane type pump having a casing with a cylindrical chamber to receive a plurality of pumping elements including a shaft with a slotted rotor with movable vanes, bearings for said shaft, a movable ring surrounding the rotor, and a pair of pressure plates disposed one at each side of and spanning the rotor and movable ring, each of said plates having an arcuate pressure port and an arcuate suction port with corresponding vane balancing ports, means between the outer side of each pressure plate and adjacent wall of the casing defining a peripherally sealed kidney-shaped pressure area encompassing the pressure port and balancing port to confine fluid under pump pressure to urge the pressure plates toward the rotor and oppose the pressure generated by the pump, a spacer member against which said pressure plates abut to limit inward movement of the pressure plates and prevent binding of the movable ring, means sealing the space surrounding the suction port and associated balancing port comprising an O-ring between the outer face of each pressure plate and adjacent casing wall, opposed fluid pistons for controlling the position of the movable ring with each piston having an end engaging the movable ring, and means for injecting pumped fluid into said bearings including a radial slot on the inner face of each pressure plate extending radially outward from a central opening in the pressure plate to a point short of the pressure vane balancing port, and a radial notch on each side face of the rotor which spans said pressure vane balancing port and the radial slot once in each revolution of the rotor.

19. A pump as defined in claim 18 including a thrust block loosely mounted in said casing for opposing forces on the movable ring created by the pumping action, said References Cited UNITED STATES PATENTS 3,052,189 9/ 1962 Head. 2,600,6 3 3 6/ 1952 French. 2,612,114 9/ 1952 Ernst. 2,685,256 8/ 1954 -Humphreys. 2,764,941 10/ 1956 Miller et a1. 2,955,542 10/ 1960 Gaubatz. 3,451,344 6/ 1969 Trick.

WILLIAM L. FREEH, Primary Examiner W. I. GOODLIN, Assistant Examiner US. Cl. X.R. 4l8-82, 132, 178 

